1. Field of the Invention
The present invention relates to a substrate processing apparatus and a substrate processing method for successively processing a plurality of substrates, such as semiconductor substrates, glass substrates for liquid crystal display devices, glass substrates for photomasks, substrates for optical disks or the like.
2. Description of the Background Art
As well known, products such as semiconductors, liquid crystal displays or the like are manufactured by performing a series of processings including cleaning, resist coating, exposure, development, etching, formation of interlayer insulating films, thermal processing, dicing and the like on the above substrates. Generally, a substrate processing apparatus consists of processing units for performing these processings and transport robots for transporting the substrates to the processing units. For example, an apparatus consisting of a coating unit for performing a resist coating process on the substrates, a development unit for performing a development process on the substrates and a transport robot for transporting the substrates between these units is a so-called coater & developer, which is widely used.
As one exemplary substrate processing apparatus, Japanese Patent Application Laid Open Gazette No. 2005-93653, for example, discloses a coater & developer in which a plurality of cells are arranged in parallel, one of which is constituted of one transport robot and a plurality of processing units from/to which the transport robot transports substrates, and a substrate passing part is provided between the cells, to pass the substrates from/to the transport robots of the adjacent cells via the substrate passing part.
Though the apparatus disclosed in Japanese Patent Application Laid Open Gazette No. 2005-93653 is one for performing the resist coating process and the development process on substrates, it is possible to apply a like cell structure in which a plurality of cells are connected to one another via the substrate passing parts to devices for performing other types of processings, such as a cleaning device for cleaning substrates with a brush. Specifically, the cleaning device has a construction in which an indexer cell for accumulating unprocessed substrates and processed substrates and a cleaning cell provided with a brush cleaning unit are connected to each other via a substrate passing part. The indexer cell and the cleaning cell are provided with respective dedicated transport robots.
In the substrate processing apparatus having such a cell structure as discussed above, if the number of process steps performed in each cell becomes larger, the number of transporting processes using the transport robot increases and the transport becomes a rate-limiting factor. In order to solve this phenomenon, some sort of substrate processing is performed in the substrate passing part between the adjacent cells, to reduce the number of process steps to be performed in each cell. Specifically, the substrate passing part also has a function as a substrate processing part as well as the original function of passing substrates between the cells. In a cleaning device in which a brush cleaning unit is provided in a cell, for example, a process of reversing front and back sides of a substrate may be performed in the substrate passing part. Since the substrate processing which is conventionally performed in the cell is performed in the substrate passing part, the number of process steps to be performed in the cell decreases and the transport load of the transport robot is reduced.
There arises a new problem, however, that if the substrate passing part performs some sort of substrate processing, the transport robot can not load the next substrate into the substrate passing part, in other words, a transport operation for the next substrate can not be started until the substrate processing is finished. The simplest method to solve this problem is to increase the number of passing parts each of which also performs some sort of substrate processing, but since the reverse passing part which is a passing part for reversing front and back sides of a substrate has a large size, it is not easy to increase the number of stages for the passing parts for reasons of layout of the whole apparatus. If the vertical-direction operating range of either one of the transport robots which access the substrate passing part is limited, especially, it is very hard to configure a multistage structure of the reverse passing parts for reversing front and back sides of substrates.